Apparatus for through ringing on telephone trunk-lines.



PATENTED SEPT. 13, 1904.

J. L. MOQUARRIE. APPARATUS FOR THROUGH RINGING ON TELEPHONE TRUNK LINES.

APPLICATION FILED DEO.14. 1901.

2 SHEETS-SHEET 1.

NO MODEL.

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WITNESSES:

PATENTED SEPT. 13, 1904.

J. L. McQUARRIE. APPARATUS FOR THROUGH RINGING ON TELEPHONE TRUNK LINES.

APPLICATION FILED DEO.14, 1901.

2 SBEETS-SHEET 2.

lira.

NO MODEL.

.Mllllllli m m m Nwm [R r WM A u Q a M 2L M J UNITED STATES Patented September 13, 1904.

PATENT OEETCE.

ELECTRIC COMPANY, OF CHICAGO, ILLINOIS,

ILLINOIS.

A CORPORATION OF APPARATUS FOR THROUGH RINGING ON TELEPHONE TRUNK-LINES.

SPECIFICATION formingpart of Letters Patent No. 769,763, dated September 13, 1904.

Application filed December 14, 1901. Serial No. 85,924. (No model.)

To It whom it Wtay concern:

Be it known that I, J AMES L. MGQUARRIE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Apparatus for Through Ringing on Telephone Trunk-Lines, of which the following is a full, clear, concise, and exact description.

My invention relates to a telephone-exchange system, and more particularly to a system wherein the answering operator who makes use of a trunk-line extending to a distant board for completing a connection to a subscribers line terminating at such distant board signals the called station directly instead of having a trunk operator do the signaling. This operation is commonly called through ringing.

The object of my invention is to provide an improved system for through ringing by which the answering operator may transmit a call-signal to any station of a party-line terminating at the distant board without liability of confusion and signaling of the wrong station.

My invention is particularly designed to be applied to asystem for through ringing, such as that shown is an application of \Valter O. Pennell for United States Letters Patent, Serial No. 37,4574, tiled November 23, 1900, for improvement in apparatus for telephone trunk-lines, and I will describe my invention in connection with Pennells system. In that system the terminal plug of the trunk-line at the receiving-board or B position is equipped with a ringing-key and an electromagnetic switch adapted to connect such ringingkey with the trunk-line, and so with the connected telephone-line over which the call-sig-. nal is to be sent, and means are provided controlled at the distant switchboardthat is, at the long-distance or answering switchboard for operating said electromagnetic switch. The calling-key at the trunking-board may be a party-line key, and in case a station of the party-line is to be signaled the trunking operator must assist the answering operator to the extent of placing said party-line key in a position to apply the proper specialized current which will operate the signalbell at the particular station desired to the exclusion of the other stations.

My invention has in view an improvement in the system whereby the trunking operator will be compelled to set the ringing-key at the establishment of each new connection in order that the called station may be signaled, so that the possibility of the wrong station being signaled by the key being left in the position which it was given during some previous connection will be avoided.

Hy invention further aims to avoid confusion in signaling which might be caused by the answering operator beginning to ring be for the trunk-plug is inserted in the jack of the called line at the trunking-board. WVhen this happens, ringing-current might be momentarily applied to the wrong line conductor, due to the tip of the plug grazing the longer line-spring of the jack as it is being inserted.

In accordance with my invention the partyline ringing-key at the trunking-board cannot be set until the plug is inserted. After the plug is inserted, however, the party-line ringing-key having been manually set will be locked in such position as long as the plug is in the jack and will automatically be released when the plug is removed, leaving the circuit through the selective key normally open, so that at each connection the key must be depressed in order that signaling-current may be applied when the electromagnetic switch is operated.

1 will describe my invention more particularly by reference to the accompanying drawings, in which Figure 1 is a circuit diagram illustrating two switchboards with a trunk-line uniting them, a calling subscribers line terminating at the answering-board, and a party-line terminating at the trunking-board, the system being equipped and operating in accordance with my invention. Fig. 2 is an elevation, par tially in section, of the party-line ringing-key,

showing the electromagnetic device whereby a plunger thereof once depressed may be held or set until electrically released. Fig. 3 is a transverse sectional view on line 3 3 of Fig. 2. Fig. 4, is a diagram showing how the difierent sets of switch-springs operated by the partyline ringing key may be associated with sources of specialized signaling-current to adapt the key for selectively signaling any one of the several stations of a party-line.

Similar characters of reference are used to designate the same parts wherever they are shown.

Referring first to Fig. 1, the trunk-line extends in two limbs 1 2 from the answeringswitchboard A to the receiving-switchboard or trunking-board B. A telephone-line a is shown extending from a telephone-substation A to the board A, and in the right-hand portion of the figure a party-line b is shown extending from four stations B B B B* to a spring-jack at the trunking-board B. In accordance with the usual engineering practice the trunk-line terminates in a spring-jack c at the answering-board and in a trunk-plug (Z at the trunking-board. The plug (Z has the usual tip, ring, and sleeve contacts (Z (Z (Z the tip and ring contacts, respectively, forming the terminals of the trunk-line conductors l 2 and the third contact (Z forming the terminal of a local switchboard-circuit, which is completed when the plug is inserted in any spring-jack. The limbs 1 2 of the trunk-line terminate at the answeringboard in the short and long line springs 0' 0 respectively, of the springjack 0. The jack 0 also has the usual third contact-thimble 0 which is adapted to be engaged by the shank of a plug inserted therein, and in the system shown this contact 0 forms the terminal of a conductor 3 of the trunk-line which forms a part of the supervisory signaling-circuit. The usual pair of plugs united by the link conductors of a cordcircuit is shown at the answeringboard A, whereby any two lines may be united by plugging into the spring-jacks thereof. The trunk- 7 line is divided at the trunking-switchboard B by a repeating-coil e in accordance with the usual practice. One set of windings of the repeating-coil are connected in the circuit of the trunk-line leading to the answering-switchboard and the other set of windings are connected with the circuit leading to the trunkplug (Z. The circuit of the trunk-line between the repeating-coil and the trunk-pin g is by way of the armatures f f of the electromagnetic switch f. The armatures of said switch are connected with the tip and ring contacts (Z d respectively, of the trunk-plug, and the back contacts of said armatures are connected with the portions of conductors 1 2, respectively, which lead tovthe repeating-coil. The front contacts of the relay f, against which the armatures f f are moved when the relay is eX- cited, form the terminals of a bridge-circuit 4, leading to the several contacts of the partyline ringing-key g. The relay f is-thus adapted when energized to sever the trun k line and connect the terminals thereof which lead to ilzlhe trunk-plug with the party-line ringing- *ey. be selectively signaled by depressing one of the plungers of the ringing key and then bringing about the actuation of the electromagnetic switchf'to connect the ringing-key with the calling-plug, and so with the line to be signaled. The mag-net of switch f is included in a local circuit 5 from the central battery it, and this local circuit 5 is controlled by a relay k, which is connected in a bridge of the trunk-line and is responsive to ringingcurrent sent over the trunk-line from the answering-board. The plug-circuit at the answering-board is provided with an ordinary ringing-key by which current from the generator G may be applied to the trunk-line. When the answering operator at board A depresses her ringing-key, the current thus applied to the line serves to actuate the relay k at the board 'B, which, drawing up its armature, closes the local circuit 5 and brings about the actuation of the electromagnetic switch f, whereby the ringing-key g is connected with the called line, the current applied to the called line being determined by the particular set of switch-springs which may have been manually actuated by the B operator.

As shown in Figs. 2, 3, and 4:, the ringingkey comprises five sets of switch-springs, each of which is adapted to be actuated by a plunger which carries a wedge for forcing the main springs apart. Five individual keys g g g g g are thus provided, each of which has a pair of main contact-springs with normal resting contacts and alternate contacts. The two main contact-springs of the first key g of the series are connected, respectively, with the front contacts of the electromagnetic switch f. The switch-springs of each succeeding key are connected with the normal resting .contacts of the preceding key, and the other or alternate contacts of each key are connected with a special source of signalingcurrent, as shown in Fig. 4, and in accordance with well-understood engineering practice, whereby the signal-bell at any one of the stations of a party-line may be selectively operated. The party-line shown in Fig. 1 has four stations, and the first four keys g g g g are adapted when operated to signal the stations B B B B, respectively, of the party-line. The last key g of the series is for use when the trunk-line is to be connected with an ordinary subscribers line, and this key is adapted to apply a grounded source of ordinary alternating ringing-current to the ring-contact of the plug. Each of the plungers Z Z of the party line ringing-key carries at its lower end an iron armature Z. Immediately under the row of plungers is mounted the looking or setting Any station of a party-line may thus IIS magnet m, which consists of two long iron bars m m, disposed parallel to one another and joined by three core-piecesm? A magnetizing-helix surrounds each core-piece, and these helices are connected together in series and included in the circuit of a conductor 6, which leads from the free pole of the grounded battery /& to the third contact (Z of the trunkplug (Z. W' hen the magnet is energized by the current from battery it flowing through the windings thereof, it is not strong enough to draw down to it from their normal positions the armatures Z Z; but if while the magnet on is energized one of the plungers is depressed the armature will stick to the polepieces of the magnet, and the plunger will thus be held down. lVhen the current through the magnet ceases, the armature will be released and the plunger, impelled by the elasticity of the contact-springs which it operates, will be moved up again to its normal position. In Fig. 2 I have shown the fourth plunger of the series depressed and held by the magnet. The third contact of the springjack of each subscribers line is connected to earth by a conductor 7, which in the case of the relay-switchboard includes the cut-off relay of the line. WVhen the trnnk-plug (Z is inserted in the spring-jack of any line, therefore, a local circuit 6 7 is completed in registering contacts of the plug and jack, and in accordance with my invention this circuit includes the winding of the retaining-magnet 7/1.

The operation of the system may be reviewed briefly as follows: hen the long-distance operator at the A board desires to have a connection made with a called snbscribers line which terminates at the B board, she inserts the calling-plug of her pair into the spring-jack c of the trunk-line leading to the distant board and gives her order for the line wanted to the B operator over an order-wire. The order-wire is not shown in the drawings, since it is well known in the art and takes no part directly in the operation of this invention. Having received the order, the operator plugs into the spring-jack of the line wanted and depresses one of the plungers of the ringing-key 9, according to the station which it is desired to signal. If the called station is on an individual line, the operator will depress the last key The A operator is now able to signal the called station directly by depressing her ordinary ringing-key n in her cord-circuit. Calling-current from generator G traverses the magnet-winding of relay l! at the trunking-board. This relay closes the local circuit 5, and the electromagnetic switchf is operated, thus connecting the ringing-key g with the trunk-plug, and so with the called line, the special current applied to the called line being determined by the particular plunger which has been depressed. Since the holding down of the plunger of the ringingkey is dependent upon the magnet on being excited, it will be understood that the ringing-key cannot be set until the plug has been inserted in the jack of the called line; but after the plug is inserted when one of the plungers of the ringing-key is depressed it is held down as long as the plug remains in the jack, the application of ringing-current to the line, however, being determined by the operation of the electromagnetic switch f, which is controlled from the answering-board. The long-distance operator at the A board may ring the called station as long or as frequently as may be desired. The supervision of the connection will remain with the long-distance operator. The disconnect-signal of the called party will be conveyed back to the A board over a signaling-circuit, which is shown in the drawings, but which need not be particularlydescribed.

It will be observed that the chances of confusion in transmitting call-signals are considerably lessened by my invention, since the circuit through the selective key is normally open and the key must be depressed for each connection and when depressed remains set as long as the plug is in the jack. \Vhen the plug is removed, the depressed key returns automatically to its normal position.

Having thus described my invention, 1 claim as new, and desire to secure by Letters Patent, the following:

1. The combination with two switchboards, subscribers telephone-lines centering at each board, a trunk-line extending between the boards, means at one board for connecting a calling-line to the trunk-line and means at the other board for connecting the trunk-line to a called subscribers line, of a party-line ringing-key and sources of calling-current controlled thereby at the last-mentioned board, an electromagnetic switch adapted to connect the ringing-key with the trunk-line to signal the called line, said ringing-key being adapted to determine the character of the callingcurrent to be applied by the electromagnetic switch, means controlled at the distant board for operating said electromagnetic switch, a magnet associated with the party-line key and mechanism operated by said magnet for locking the key in the position to which it may have been set, and a local circuit including a source of current for exciting said magnet, closed in making connection from the trunkline to the called line.

2. The combination with a party telephoneline and a spring-jack terminal therefor at an exchange-switchboard, of a plug and plug-circuit for making connection with the line at the spring-jack thereof, a party-line ringingkey and sources of specialized current controlled thereby for signaling any substation of the telephone line, an electromagnetic switch adapted to connect the ringing-key and its controlled source of current with the plugcircuit, means controllable from a distant point for operating said electromagnetic switch, a during the continuance of the plug in the magnet associated with the ringing-key and spring-jack. I mechanism: operated by said magnet for lock- In witnesswhereof I hereuntorsubscribe-my ing, the key in the position to'which it may name this 30th day of" September, A. D: 1901.

'5- have been set, and a local circuit including JAMES MGQUARRIE.

said magnet and a source of current, closed Witnesses: inregistering contacts of the plug and spring- DUNCAN E. WILLETT,

jack, whereby the ringing-key remains set EDWIN SMXTHE. 

